IgG Fc Glycosylation Patterns of Preterm Infants Differ With Gestational Age

Immunization technologies: Time to consider new preventative solutions for respiratory syncytial virus infections

New technologies for the prevention of infectious diseases are emerging to address unmet medical needs, in particular, the use of long-acting monoclonal antibodies (mAb) to prevent Respiratory Syncytial Virus (RSV) lower respiratory tract disease in infants during their first RSV season. The lack of precedent for mAbs for broad population protection creates challenges in the assessment of upcoming prophylactic long-acting mAbs for RSV, with associated consequences in legislative and registration categorization, as well as in recommendation, funding, and implementation pathways. We suggest that the legislative and regulatory categorization of preventative solutions should be decided by the effect of the product in terms of its impact on the population and health-care systems rather than by the technology used or its mechanism of action. Immunization can be passive and active, both having the same objective of prevention of infectious diseases. Long-acting prophylactic mAbs work as passive immunization, as such, their recommendations for use should fall under the remit of National Immunization Technical Advisory Groups or other relevant recommending bodies for inclusion into National Immunization Programs. Current regulations, policy, and legislative frameworks need to evolve to embrace such innovative preventative technologies and acknowledge them as one of key immunization and public health tools.

Rheumatoid arthritis and the risk of preterm birth

During pregnancy, many diseases are correlated with different adverse outcomes. In turn, pregnancy affects the body, leading to increased disease susceptibility. This interplay between diseased states and pregnancy outcomes is illustrated in the effect of the chronic autoimmune disorder, rheumatoid arthritis (RA), and the adverse outcome, preterm birth (PTB). RA is a systemic disorder characterized by inflammation of the joints and other body organs. Joint pain and swelling are the most prominent manifestations of RA during pregnancy. However, the exact role of RA on PTB among pregnant women has yet to be established. This review highlighted the immunologic mechanisms involved in PTB in pregnant patients with RA. The immune cell population in pregnant women with RA exhibited higher activity of macrophages, dendritic cells, neutrophils, helper T (Th) 1 cells, and Vδ1 cells, but lower activity of CD4 + CD25^high T regulatory (CD24 + CD25^high T_reg ), Th2, and Vδ2 cells. Increased pro-inflammatory cytokines IL-6, TNF-α, and IFN-γ and decreased anti-inflammatory cytokines IL-12 and IL-10 are also exhibited by pregnant patients with RA. This review also discussed factors that may predict the risk of PTB in RA. These include disease activity and severity of RA, laboratory parameters (cytokines and immune cell population), and sociodemographic factors such as ethnicity, smoking, alcohol intake, and the level of education. Current findings on the underlying immunological mechanisms of RA can help identify possible strategies to prevent PTB.

Immunoglobulin G and subclasses placental transfer in fetuses and preterm newborns: a systematic review

Immunoglobulin G (IgG) and subclasses are the only class of antibodies capable of crossing placenta and providing protection against neonatal infectious diseases, especially in premature infants. This systematic review aimed to review the literature concerning the transplacental transfer of IgG and its subclasses in fetuses and preterm newborns and compare the results with data from term neonates. Eleven studies were included in the final review. Most studies demonstrated a lower transplacental passage of IgG2 than other subclasses in term and preterm newborns and a more efficient passage of total IgG and IgG1 after 37 weeks of gestational age. These results elucidate the physiology of IgG subclass transfer during pregnancy and may explain one of the reasons preterm newborns are especially susceptible to specific pathogens, such as encapsulated bacteria.

HIV-associated alterations of the biophysical features of maternal antibodies correlate with their reduced transfer across the placenta

BACKGROUND

Human Immunodeficiency Virus (HIV) infection during pregnancy is associated with reduced transplacental transfer of maternal antibodies and increased risk of severe infections in children who are exposed and uninfected with HIV (CHEU). The basis of this reduced transfer of maternal immunity has not yet been defined but could involve modifications in the biophysical features of antibodies.

OBJECTIVE

To assess the impact of maternal HIV infection on the biophysical features of serum IgG and transplacental antibody transfer.

METHODS

Maternal serum IgG subclass levels, Fc glycosylation, Fc Receptor (FcR) binding, and transplacental transfer of pathogen-specific maternal IgG were measured in pregnant women living with HIV (WWH) and pregnant women testing negative for HIV (WNH) in Cape Town, South Africa.

RESULTS

Maternal antibody profiles were strikingly different between pregnant WWH and WNH. Antibody binding to FcγR2a and FcγR2b, IgG1 and IgG3 antibodies, and agalactosylated antibodies were all elevated in WLHIV, whereas digalactosylated and sialylated antibodies were reduced as compared to pregnant WNH. Antibody features that were elevated in WWH were also correlated with reduced transplacental transfer of vaccine antigen-specific antibodies.

CONCLUSION

HIV infection is associated with marked alterations of biophysical features of maternal IgG and reduced placental transfer-potentially impairing antimicrobial immunity.

RSV Prevention in All Infants: Which Is the Most Preferable Strategy?

Respiratory syncytial virus (RSV) causes a spectrum of respiratory illnesses in infants and young children that may lead to hospitalizations and a substantial number of outpatient visits, which result in a huge economic and healthcare burden. Most hospitalizations happen in otherwise healthy infants, highlighting the need to protect all infants against RSV. Moreover, there is evidence on the association between early-life RSV respiratory illness and recurrent wheezing/asthma-like symptoms As such, RSV is considered a global health priority. However, despite this, the only prevention strategy currently available is palivizumab, a monoclonal antibody (mAb) indicated in a subset of preterm infants or those with comorbidities, hence leaving the majority of the infant population unprotected against this virus. Therefore, development of prevention strategies against RSV for all infants entering their first RSV season constitutes a large unmet medical need. The aim of this review is to explore different immunization approaches to protect all infants against RSV. Prevention strategies include maternal immunization, immunization of infants with vaccines, immunization of infants with licensed mAbs (palivizumab), and immunization of infants with long-acting mAbs (e.g., nirsevimab, MK-1654). Of these, palivizumab use is restricted to a small population of infants and does not offer a solution for all-infant protection, whereas vaccine development in infants has encountered various challenges, including the immaturity of the infant immune system, highlighting that future pediatric vaccines will most likely be used in older infants (>6 months of age) and children. Consequently, maternal immunization and immunization of infants with long-acting mAbs represent the two feasible strategies for protection of all infants against RSV. Here, we present considerations regarding these two strategies covering key areas which include mechanism of action, "consistency" of protection, RSV variability, duration of protection, flexibility and optimal timing of immunization, benefit for the mother, programmatic implementation, and acceptance of each strategy by key stakeholders. We conclude that, based on current data, immunization of infants with long-acting mAbs might represent the most effective approach for protecting all infants entering their first RSV season.

Effect of Oropharyngeal Administration of Colostrum in Premature Newborns ≤32 Weeks of Gestation on the Immune Response and Neonatal Morbidity: A Double-Blind Randomized Clinical Trial

INTRODUCTION

The mother's colostrum carries immunological components, such as cytokines and immunoglobulins (Igs), derived from the maternal circulation with bacteriostatic properties.

OBJECTIVE

The objective of this study was to evaluate the effect of oropharyngeal administration of colostrum (OPAC) vs. placebo in the first 4 days of life in premature newborns ≤32 weeks of gestation on serum Ig concentration, neonatal morbidity, and total days of hospitalization.

HYPOTHESIS

The OPAC increases serum Igs and decreases morbidity and total days of hospitalization.

MATERIALS AND METHODS

A double-blind randomized controlled trial was carried out. Participants were randomly assigned to one of the two groups, namely, group 1: placebo (P) (n = 50) and group 2: colostrum (C) (n = 46). A blood sample was obtained at baseline and 7 and 28 days of life to quantify immunoglobulin G (IgG), immunoglobulin A (IgA), and IgM. Results: The C group showed an increase in serum IgA on day 28 expressed as median and [interquartile range]; C: 25 [12-35] vs. P: 11 [8-18], p < 0.001. There were no significant differences in neonatal morbidity. Newborns in the colostrum group showed the completed enteral feeding earlier (days), C: 13.9 ± 7 vs. P: 17.4 ± 8.4, p < 0.04; they reached the birth weight earlier, C: 10.9 ± 2.8 vs. P: 12.9 ± 4, p < 0.01, and had less days of hospitalization, C: 60.2 ± 33.8 vs. P: 77.2 ± 47.3, p < 0.04. Neonatal mortality was lower in the colostrum group than the placebo group 0% vs. 12%, respectively, without a statistical difference (p = 0.06).

CONCLUSION

In premature newborns ≤32 weeks of gestation, the OPAC within 4 days after birth increases serum IgA concentration at day 28 compared to placebo. Similarly, OPAC decreased the days to complete enteral feeding and reach the birth weight and total days of hospitalization.

CLINICAL TRIAL REGISTRATION

[https://clinicaltrials.gov/ct2/show/NCT03578341], identifier: [NCT03578341].

Estrogen-Driven Changes in Immunoglobulin G Fc Glycosylation

Glycosylation within the immunoglobulin G (IgG) Fc region modulates its ability to engage complement and Fc receptors, affording the opportunity to fine-tune effector functions. Mechanisms regulating IgG Fc glycans remain poorly understood. Changes accompanying menarche, menopause, and pregnancy have long implicated hormonal factors. Intervention studies now confirm that estrogens enhance IgG Fc galactosylation, in females and also in males, defining the first pathway modulating Fc glycans and thereby a new link between sex and immunity. This mechanism may participate in fetal-maternal immunity, antibody-mediated inflammation, and other aspects of age- and sex-specific immune function. Here we review the changes affecting the IgG Fc glycome from childhood through old age, the evidence establishing a role for estrogens, and research directions to uncover associated mechanisms that may inform therapeutic intervention.

Maternal Mental Disorders and Pediatric Infectious Diseases: A Retrospective Cohort Study

BACKGROUND

Maternal stress and depression are associated with infections in offspring, but there is a paucity of data for other mental disorders.

METHODS

We conducted a retrospective cohort study of 832,290 children born between 2006 and 2016 in hospitals of Quebec, Canada. We identified maternal mental disorders before and during pregnancy, and admissions for otitis media, pneumonia, infectious enteritis and other infections in children before 13 years of age. We used Cox proportional hazards regression to estimate hazard ratios (HRs) with 95% confidence intervals (CI) for the association between maternal mental disorders and the risk of pediatric infectious diseases, adjusted for maternal age, comorbidity, socioeconomic disadvantage, and other confounders.

RESULTS

The incidence of pediatric infection hospitalization was higher for maternal mental disorders compared with no disorder (66.1 vs. 41.1 cases per 1000 person-years). Maternal mental disorders were associated with 1.38 times the risk of otitis media (95% CI: 1.35-1.42), 1.89 times the risk of bronchitis (95% CI: 1.68-2.12), and 1.65 times the risk of infectious enteritis in offspring (95% CI: 1.57-1.74). Stress and anxiety disorders (HR 1.49, 95% CI: 1.46-1.53) and personality disorders (HR 1.55, 95% CI: 1.49-1.61) were more strongly associated with the risk of pediatric infection hospitalization than other maternal mental disorders. Associations were prominent in the first year of life and weakened with age.

CONCLUSIONS

Maternal mental disorders are risk factors for infectious disease hospitalization in offspring. Women with mental disorders may benefit from psychosocial support to reduce the risk of serious infections in their children.

Antibody glycosylation in pregnancy and in newborns: biological roles and implications

PURPOSE OF REVIEW

Glycosylation patterns have the potential to affect the function of antibody, antibody half-life and transplacental transfer from mother to foetus. Here, we review recent advances in our understanding of how glycosylation patterns of antibodies may be altered during pregnancy, vaccination and infection.

RECENT FINDINGS

During pregnancy, there is preferential transplacental transfer of natural killer (NK) cell-activating antibodies that are galactosylated and sialylated, against both bacterial and viral antigens. Markers of NK cell function are also associated with a higher abundance of galactosylation and sialylation in respiratory syncytial virus-specific IgG, compared with total IgG, in infants up to 7 months of age which may suggest a role for NK-cell activating antibodies as important mediators of immunity during early infancy. Differential glycosylation patterns have been observed in some respiratory conditions, as increased nongalactosylated antibodies have been associated with the development of chronic inflammatory bronchopulmonary dysplasia (BPD) in preterm infants. Glycosylation patterns in children appear age-dependent, which could modulate the effector function of IgG. The clinical relevance of these findings needs to be established.

SUMMARY

Glycosylation plays a key role in mediating antibody function. Glycosylation patterns associated with positive outcomes from infection in mothers and infants could inform the design of the next generation of vaccines for use in pregnancy and infancy. SDC VIDEO LINK:: http://links.lww.com/COID/A29.

The Potential Role of Nonhuman Primate Models to Better Comprehend Early Life Immunity and Maternal Antibody Transfer

Early life immunity is a complex field of research and there are still gaps in knowledge regarding the detailed mechanism of maternal antibody transfer, the impact of maternal antibodies on infant vaccine responses and the ontogeny of human early life immunity. A comprehensive understanding is necessary to identify requirements for early life vaccines and to improve early childhood immunization. New immunological methods have facilitated performing research in the youngest, however, some questions can only be addressed in animal models. To date, mostly murine models are used to study neonatal and infant immunity since they are well-described, easy to use and cost effective. Given their limitations especially in the transfer biology of maternal antibodies and the lack of infectivity of numerous human pathogens, this opinion piece discusses the potential and prerequisites of the nonhuman primate model in studying early life immunity and maternal antibody transfer.

Sweet Rules: Linking Glycosylation to Antibody Function

Antibodies produced upon infections with pathogenic microorganisms are essential for clearing primary infections and for providing the host with long-lasting immunity. Moreover, antibodies have become the most widely used platform for developing novel therapies against cancer and autoimmunity, requiring an in-depth understanding of how antibodies mediate their activity in vivo and which factors modulate pro- or anti-inflammatory antibody activities. Since the discovery that select residues present in the sugar domain attached to the immunoglobulin G (IgG) fragment crystallizable (Fc) region can modulate both, pro- and anti-inflammatory effector functions, a wealth of studies has focused on understanding how IgG glycosylation is regulated and how this knowledge can be used to optimize therapeutic antibody activity. With the introduction of glycoengineered afucosylated antibodies in cancer therapy and the initiation of clinical testing of highly sialylated anti-inflammatory antibodies the proof-of-concept that understanding antibody glycosylation can lead to clinical innovation has been provided. The focus of this review is to summarize recent insights into how antibody glycosylation is regulated in vivo and how select sugar residues impact IgG function.

Immunoglobulin G Glycosylation Changes in Aging and Other Inflammatory Conditions

Among the multiple roles played by protein glycosylation, the fine regulation of biological interactions is one of the most important. The asparagine 297 (Asn₂₉₇) of IgG heavy chains is decorated by a diantennary glycan bearing a number of galactose and sialic acid residues on the branches ranging from 0 to 2. In addition, the structure can present core-linked fucose and/or a bisecting GlcNAc. In many inflammatory and autoimmune conditions, as well as in metabolic, cardiovascular, infectious, and neoplastic diseases, the IgG Asn₂₉₇-linked glycan becomes less sialylated and less galactosylated, leading to increased expression of glycans terminating with GlcNAc. These conditions alter also the presence of core-fucose and bisecting GlcNAc. Importantly, similar glycomic alterations are observed in aging. The common condition, shared by the above-mentioned pathological conditions and aging, is a low-grade, chronic, asymptomatic inflammatory state which, in the case of aging, is known as inflammaging. Glycomic alterations associated with inflammatory diseases often precede disease onset and follow remission. The aberrantly glycosylated IgG glycans associated with inflammation and aging can sustain inflammation through different mechanisms, fueling a vicious loop. These include complement activation, Fcγ receptor binding, binding to lectin receptors on antigen-presenting cells, and autoantibody reactivity. The complex molecular bases of the glycomic changes associated with inflammation and aging are still poorly understood.

Maternal Immunization: Nature Meets Nurture

Vaccinating women in pregnancy (i.e., maternal immunization) has emerged as a promising tool to tackle infant morbidity and mortality worldwide. This approach nurtures a 'gift of nature,' whereby antibody is transferred from mother to fetus transplacentally during pregnancy, or postnatally in breast milk, thereby providing passive, antigen-specific protection against infections in the first few months of life, a period of increased immune vulnerability for the infant. In this review, we briefly summarize the rationale for maternal immunization programs and the landscape of vaccines currently in use or in the pipeline. We then direct the focus to the underlying biological phenomena, including the main mechanisms by which maternally derived antibody is transferred efficiently to the infant, at the placental interface or in breast milk; important research models and methodological approaches to interrogate these processes, particularly in the context of recent advances in systems vaccinology; the potential biological and clinical impact of high maternal antibody titres on neonatal ontogeny and subsequent infant vaccine responses; and key vaccine- and host-related factors influencing the maternal-infant dyad across different environments. Finally, we outline important gaps in knowledge and suggest future avenues of research on this topic, proposing potential strategies to ensure optimal testing, delivery and implementation of maternal vaccination programs worldwide.